To obtain maximum thrust efficiency from a rocket engine it is necessary to equip the engine with a divergent exit nozzle configured for the ambient pressure in which the rocket operates. Rocket engines propelling second and later stages of missiles are required to operate at low ambient pressures and must be equipped with exit nozzles of substantial length and exit diameter.
In order to make maximum utilization of the valuable space within the body of a missile and to reduce its overall length it has been proposed that the nozzle for the second and possibly later stages be made in sections and collapsed, or telescoped, on its self to reduce its length. This arrangement requires that the nozzle be provided with a structure for supporting the telescope sections and for propelling them to their extended positions when the rocket engine is fired.
U.S. Pat. No. 4,213,566, granted July 22, l980, to L. E. Miltenberger for "Nested Cone Extendible Nozzle System for a Rocket Motor" discloses a system of longitudinal tracks for supporting and allowing sliding movement of the nozzle sections in relation to each other. The nozzle sections are deployed by aerodynamic drag panels extending into the exhaust path of the rocket. U.S. Pat. No. 3,346,186, granted Oct. 10, 1967, to D. L. Fulton et al, for "Extensible Rocket Nozzle Comprised of a Coated Flexible Mesh Subsequently Deployed and Heated to Become Impermeable", and U.S. Pat. No. 4,184,238, granted Jan. 22, 1980, to L. F. Carey for "Method of Making an Extendible/Expandable Nozzle for Rocket Engines" propose that the extendable portion of the nozzle be formed of flexible material which can be collapsed back on a nozzle base. The skirt-like extensions of the nozzle structures of these patents are supported and deployed by a plurality of fluid actuated piston and cylinder devices mounted on the nozzle. A somewhat different approach to a foldable nozzle is disclosed in U.S. Pat. No. 4,349,155, granted Sept. 14, 1982 to P. Donguy for "Unfoldable Divergent Nozzle for a Rocket Engine". This patent suggests that the nozzle wall be divided into a multiplicity of panels, or petals, that are articulated, i.e. hingedly connected, in such a manner that the panels can be folded against each other to shorten the nozzle.
The principal shortcoming of the nozzle section supporting systems disclosed in the prior art is that none of these systems has inherent structural stability. The systems are composed of a plurality of components which do not interact to support and guide the nozzle sections. The nozzle sections are, of course, subjected to severe transient loads from aerodynamic and inertial forces. To handle such loads with the prior supporting systems components having considerable bulk and weight are employed. Thus, as to each of these prior structures, rather massive components are required in order to support the nozzle segments, propel them along the desired deployment paths and position them correctly in their extended positions.
Another disadvantage of these prior supporting systems--particularily those employing a plurality of independent actuating mechanisms--is that simulataniety of motion of all portions of each extendable nozzle section is not assured. If one actuator acts more quickly than another actuator the nozzle section can become canted, or misaligned and full deployment may not be achieved.
There continues to be a need, therefore, for a light weight and reliable system for supporting and deploying extendable nozzle sections.